Mass plating

Mass plating is used for small workpieces to be plated in large quantities, such as nuts and bolts, but it is not used for delicate workpieces. The most widely used mass plating system is called barrel plating, where the work-pieces are loaded into a plating barrel. Other mass plating containers include plating bells and vibratory units. 

Some workpieces cannot be mass plated because of their size, shape, or special features. Rack plating means workpieces are mounted on a rack for the appropriate pretreatment plating and posttreatments. Racks are fixtures suitable for immersion in the plating solution. Rack plating is sometimes called batch plating. 

Ionic conduction may dominate the electrical behavior of materials with small electronic conductivity, and its study is useful in the investigation of lattice defects and decomposition mechanisms. In order to establish that conduction takes place by the motion of ions and not of electrons or holes, one can compare the transport of charge with the transport of mass plated out on electrodes in contact with the sample. In practice, this approach is not always feasible because of the very low conductivities associated with ionic motion. When ionic conductivity is suspected one usually attempts to vary the concentration of defects by introducing impurities. For example, for cation conduction in monovalent ionic compounds, addition of divalent cations should enhance the conductivity, since the vacancies produced (in order to ensure charge compensation) lead to enhanced diffusion of the monovalent cation. (The diffusion of a vacancy in one direction is equivalent to the diffusion of an ion in the opposite direction). 

Where a rechargeable power source is required for portable-in-use apparatus, the nickel-cadmium system is generally specified. Nickel-cadmium batteries and cells are available in a wide range of cylindrical and button sizes, and they are ideally suited to high-rate applieations. Both sintered electrode cylindrical batteries and mass plate electrode button cells constructions are available. The following discussion refers largely to the former type, since these oceupy the major part of the market. 

Sealed nickel-cadmium cells with mass plate elee-trodes have an ampere hour effieieney of approximately 72%, while those with sintered eleetrodes have approximately 84% effieieney at about 20°C. (The effeet of temperature will be diseussed later.) For this reason the charging factor for mass plate eells is 1.4 and for sintered plates 1.2 therefore to fully eharge a fully discharged cell, either 40% (1.4) or 20% (1.2) more eapaeity than has been withdrawn must be put baek into the cell. 

Button cell batteries with mass plate electrodes in plastic encapsulation ... 

Charge retention These batteries have a moderate self-discharge characteristic at normal temperatures. For applications requiring good charge retention, mass plate electrodes are preferred. 

This company supplies a range of sintered plate cylindrical cells and mass plate button cells (Tables 51.42... 

Table 51A1 Self-discharge of Table 51A2 Standard Ever Ready range cf mass plate buttcn ...

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